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Orion 120 f/8.3 thoughts?

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#26 clearwaterdave

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Posted 30 October 2019 - 12:29 PM

Thank you guys.This is the type of replies I was looking for.,

  I know this scope will not do anything the scopes I have can't do.,I just like frac's.,and I think it looks awful nice.,long and white.,lol.,Cheers.,


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#27 paul m schofield

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Posted 30 October 2019 - 04:50 PM

I recently got a great deal on a Meade LX70 R5 120mm f/8.33 OTA and put it on my LXD75 mount that has the 2" diameter legs. With the vibration pads it tracks and focuses quite easily with just a bit of swaying from the long moment arm. High power is easy, nice and smooth. The R&P focuser is adequate if the tension knob is more firm than loose. It's not bad and I'm sure a new focuser would help IF you wanted to spend the money on an inexpensive scope. I haven't had much opportunity to try it yet except on the moon, Jupiter, Saturn, and a few double stars. 

 

Jupiter is always the test. At full aperture there wasn't much color to my old eyes (I'm 72) but the view was mushy, not sharp. I made aperture stops of 100mm, 80mm, and 60mm. With the 100mm stop the image sharpened quite a bit with little loss in brightness. The highest mag with a reasonable image was 149x using my 6.7mm UWA. I put in the 80mm stop  and the image sharpened even more with multiple belts, GRS, hints of festoons and ovals similar to my 80mm Celestron/Vixen f/11.4. The moons were a delight showing different sizes. The brightness, however, was reduced as expected. My best high power again was 149x but the Meade 5.5mm (182x) surprised me when the seeing steadied. With the 60mm stop it was sharp as a tack but running out of light and the best views were at lower powers. At the 80mm stop the focal ratio is f/12.5 with a CR of 3.97. Not bad at all, even a little better than my Vixen made 80mm.

 

The moon was reasonably sharp at full aperture, even sharper with the aperture stops, but the difference wasn't as noticeable as Jupiter. Saturn was the same and powers around 200x were very good with lots of detail. Double stars were also very good. Epsilon Lyra was a beautiful four star split at 71x and even better at 113x.

 

I got an 8x50 RACI that improved finding things immensely. I did an experiment when sighting in the finder on a distant power pole. I tried all my eyepieces and all the aperture stops to see the level of color and sharpness. At full aperture the color was horrible and details fuzzy. The 100mm stop reduced the color a lot and sharpened the view. The 80mm stop showed no color to my eyes in the daytime and details were very sharp... just like on Jupiter. 

 

These scopes are great for what you pay for them. Nice aperture for DSO's and using the aperture stops planetary detail can be very pleasing. They are not Apo's, but for a few hundred bucks they are great fun and you can see a lot. ( tried to rotate the image but no success)

 

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#28 clearwaterdave

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Posted 30 October 2019 - 07:22 PM

A lot of talk about the focuser.,If it is the same as the one on the Omni and Meade 102's.,I have cleaned and adjusted them to be plenty usable for me.,I use them daily.,lookin at the birds with the Meade.,

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#29 tony_spina

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Posted 31 October 2019 - 12:13 AM

Life is too short to focus on the negatives.  If you can afford it and you are curious get the scope.  It’s a learning experience.  Besides the only person who needs to like the scope is YOU


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#30 Jon Isaacs

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Posted 31 October 2019 - 08:29 AM

Life is too short to focus on the negatives.  If you can afford it and you are curious get the scope.  It’s a learning experience.  Besides the only person who needs to like the scope is YOU

 

Dave is asking about the scope and mount, he is asking for thoughts and experiences. 

 

As a stand alone, only scope, these scopes have their place. But I've had three of them and given Dave's other scopes, I think his likely experience will be "lesson learned, now I appreciate my AT-102ED even more and maybe I'll want a 120 mm ED."

 

But the only way to find out is to buy it and at $150, that's hopefully within his budget..

 

One problem with these scopes: Shipping them is expensive. Buying a $150 used eyepiece and selling it makes sense because shipping is less than $20. Buying this scope and mount for $150 and then selling is more of a challenge because shipping for the OTA itself might be $100 or even more.

 

Jon


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#31 clearwaterdave

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Posted 31 October 2019 - 08:45 AM

Life is too short to focus on the negatives.  If you can afford it and you are curious get the scope.  It’s a learning experience.  Besides the only person who needs to like the scope is YOU

That's right.,I am curious and $150 isn't gonna break me.,

  I guess I'm not ready for the minimalist approach yet.,or maybe I'm just a gear geek.,lol.,

I just read Jon's reply.,lol.,and he is correct as always.,now if that 120ed would just come up for sale here in Me..,There is a TV101 with a lot of ep's and a tripod/mount for $6000.,Naahh.,I already have a 102ed.,lol.,cheers.,I am laughin.,.,at myself.,waytogo.gif


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#32 clearwaterdave

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Posted 01 November 2019 - 09:48 AM

We set up a meet for tomorrow.,If it isn't all beat up it will come live in Industry for a while.,

   I offered him $25 extra if he would bring it up to Augusta,.Otherwise I would have passed on it.,he agreed.,Hopefully it is in good shape., The forecast looks good for tomorrow night.,lol.,Will report back when it is in the house.,cheers.,


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#33 Frisky

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Posted 01 November 2019 - 03:31 PM

Buy it if in good shape. It's pretty much the same scope as the LX70 R5 isn't it? It'll be solid on the LX70 mount. You can take it out in windy conditions that would likely raise heck with your 102mm ED if that one was on a light weight mount for grab and go. On good nights, you'll have no trouble seeing detail on Jupiter, including moon transits and the GRS. Last night, Saturn was beautiful! I've had mine out 348 nights in 19 months. I've seen quite a bit more detail than I would with a 20 inch dob I'd seldom take out. 

 

Joe


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#34 clearwaterdave

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Posted 03 November 2019 - 01:41 AM

It is in Industry.,lol.,what a tank.,a bit dusty but no worse for the ware.,

The mount seems good.,the tripod could use new legs.,a bit shaky,but my vibration pads get rid of most all of it.,and settle time is nil.,

  The views of luna and Saturn were very good at125x with the Meade zoom.,and stars looked good with the ES 24/68.,

  I think it "needs" a 2" diagonal to help with balancing.,even with an 8x50 finder (I added this)it is still a little nose heavy.,

    The focuser is ok.,not the greatest but serviceable enough for me.,My main complaint so far is the rings/mount do not use a vixen rail,.thanks Orion.,I will find a way to fix that because I kinda like the mount itself and would like to use it with other scopes.,.

  Upon reading the manual I picked up a bit more knowledge about using the eq mount.,Most all the vids on utube are about setting it up.,not about accually using it.,The number dials on this mount seem a bit better than the ones on the lx70.,But there's more to driving an eq then just setting the numbers.,and time behind the mount will be my best teacher.,

  Overall I think I got my nickel's worth.,I don't think it will be replacing any of my scopes.,but it will stay for awhile.,

  Thank you again for everyone's replies.,I felt like I knew what I was getting into after reading them.,and am glad I posted and asked.,Cheers.,

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#35 tony_spina

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Posted 03 November 2019 - 02:48 AM

make sure to check collimation.  It should be fine, but it doesn’t hurt to check.  On one of these scopes the focuser was slightly off and needed a little tweak to make it spot on


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#36 clearwaterdave

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Posted 03 November 2019 - 02:52 AM

Hi Tony.,I do not know how to do this.,I guess I should learn considering I have a "few" that I have never checked out.,they seem good to me.,but.,lol.,



#37 tony_spina

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Posted 03 November 2019 - 09:55 AM

Do a star test. You can use Polaris since it will not move for all practical purposes 

 

ideally you will want to do this without the diagonal because the diagonal may be mis-collimated as well.  Get a high power eyepiece that will give you at least a 1mm exit pupil.  So for this scope you would need a 8.3mm or smaller, like a 7mm eyepiece 

Now what you will want to do is center Polaris and the defocus the star you should see concentric rings.  

 

If if you do a Google search you can find lots of images and links.  Here is an example 

https://www.google.c...ArlVWJl6JwWpM: 

 

you should do the test with defocusing the star both from focusing inside and focusing outside from at focus.  In other words have the focus tube go in from perfect focus and have the focus tube go out from perfect focus.  Now try this with and without a diagonal and report back on what you see.  Note the the seeing condition needs to be decent in order to really see this well.  In poor conditions you will see a boiling mess


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#38 gene 4181

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Posted 03 November 2019 - 10:15 AM

  You can use a chesire eyepiece with the side opening  , shine some light in , LEAVE  the objective cap ON   and you should see a single circle  down at the end .  Overlapping circles or figure 8  and it needs tweaking ,  adjust , etc.,  With some scopes you have too enlarger the  cell attachment holes or the focuser attachment holes (small round file )    smile.gif


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#39 clearwaterdave

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Posted 03 November 2019 - 04:34 PM

I will try the star test.,If it is out.,how do I fix it?.,

  Here is my fix for the lack of the vixen rail option.,It seems good.,now I can mount 4 of my frac's on this mount instead of just this scope.,and this scope can now go on the LX70.,win win.,It took me longer to find the 2 correct size bolts in my garage than it took to make the piece.,lol.,

   

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#40 tony_spina

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Posted 03 November 2019 - 05:06 PM

How to fix fill depend on what you report back on how the out of focus rings will look like. 

 

For example if the image looks like a triangle then you have some pinched optics most likely due to the retaining ring holding the lenses is to tight.

 

As mentioned above so you have a Cheshire eyepiece/site tube?  Do you have a laser collimator?   We can use these tools to help fix the alignment of the lens and or focuser

 

Another example is due to the focuser not aligned correctly.  If you were to use a laser collimator and along with a circular paper mask on the lens with a mark or hole dead center.  When you shine the laser in the focus tube the laser should be lighting up the mark or hole.  If it is off you can loosen the screws that are holding the focuser to the tube. Then use the slight wiggle room you have to adjust until center.  Then tighten the screws

 

Like I said before tell us what you see an then we can tell you how to adjust.  Note that some issues like astigmatism may be inherent in the lens itself and we will not be able to fix


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#41 Jond105

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Posted 03 November 2019 - 05:36 PM

It took me a few hours since it was my first time ever, but having the collimating cell, you may be good if the owner already did it, if not, it’s not that hard since doing the XLT120MM I used to own. By the way, Nice scope. 


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#42 DeWayne

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Posted 03 November 2019 - 07:46 PM

First off, congratulations on getting the scope!  I hope you enjoy it as much as I do.  I noticed you got the one with the collimatable cell.  You can download the scope manual from Orion. It has instructions on how to do the collimation. Just be careful not to strip out the screws. The hex bolts in particular.  You'll need a Chesire eyepiece, unless you've got the one that was sold with the scope (I did not - I used the one for my reflector telescope.)  I fussed with the stock focuser for a few weeks before giving up on it. Maybe you'll have better luck. I tried shimming it, adjusting this and that, but there was always some "slop" that I could never completely eliminate. I still have it in a drawer if anyone wants it! 

 

I had this scope out tonight side-by-side with an Orion 90  f/10, looking at the Moon.  Sidgewick notwithstanding, the view was qualitatively better in the 120 f/8.3 v the 90 f/10.  It is true there was a noticeably more color around the bright edge of the Moon in the larger scope, but that was the only disadvantage and hardly an issue.  At similar magnifications, the view through the 120 was brighter, sharper, and more detailed.  I could see subtle tonal changes on the floor of the Sea of Serenity much more easily than through the smaller scope with the higher F/ratio, for instance.  

 

You know how it kind of seems like any scope gives it best views at medium-to-low power, and the image starts degrading as you push it higher? Get up toward the top end of the magnification range, and you can certainly find things and see things, but you can just tell the scope is starting to struggle?  The image gets dimmer, focus may get more finicky, the extra bump in magnification starts noticeably degrading detail?   Between these two scopes, I was starting to get that impression from the smaller scope, while the larger one was still looking great.  The view from the 120 reminded me more of the views through my 8" dob (which is one reason I got rid of the dob after I got the 120 refractor.)  

 

Now, the 90 EQ is a lower-end scope and it's quite possible the optical quality itself is just not as comparable to the 120.  But I've owned it for several years and always been very happy with its performance (and still am.)  It just could not keep up with the 1/3 more aperture in the 120. 

 

I find that interesting in light of the Sidgwick Standard, which someone brought up earlier.  Based on my experience with these scopes, I am not convinced the Sidgwick standard is the final word on telescope performance on planetary/lunar observation.  Maybe there is a fudge-factor somewhere to account for greater aperture as well? 


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#43 gene 4181

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Posted 04 November 2019 - 01:02 AM

 The Phillips are the pull screws  , the allen screws are the push screws .  loosen the Phillips  and adjust the allens  in or out and  then re-tighten  the Phillips  . At one time Celestron used too provide  a tool  w/  the  the scope , C 102 HD and C -4- R days    now Agena sells the refractor  chesire , shorter version without crosshairs  , but the others with  crosshairs will work ( Tectron)   there was even a section devoted too  collimating refractors in  New Perspectives on Newtonian Collimation  ,


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#44 clearwaterdave

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Posted 04 November 2019 - 02:12 AM

I was viewing the moon last night with a Meade zoom and the view was pretty darn good.,At 125x the image was very sharp.,with a bit of atmospheric waves.,I have not looked at a lot yet.,M2 was very clear.,the 2 ,11.5mag. stars below it showing easily.,

   Thank you guys for the collimation instructions.,I will see what I see.,For now it seems good but I haven't scrutinized the star views yet.,I will use my 13mm Nagler.,that way if stars look fishy I know it's not the ep,.cheers.,


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#45 clearwaterdave

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Posted 04 November 2019 - 07:31 PM

I went out after my last post and looked at the stars.,lol.,I focused in and focused out.,the star looked round.,and the same either way.,

  The sisters were very nice in the ES28/68.,With the 13Nagler the trap showed 4 stars clearly.,and all the stars in the fov looked good..,I am going to say it is ok.,

  I had the focuser apart again today and found little allen screws that press against the same piece the large thumbscrew puts pressure on.,these were in need of adjusting.,now it is much smoother.,even with the 2" stuff.,waytogo.gif

  I still haven't put it on the LX70.,cheers


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#46 beanerds

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Posted 05 November 2019 - 06:31 AM

The 120 f/8 is a really decent scope by itself at a good price and one I could've been happy with as an only scope many years back when I had the chance to get one.  But having since owned an XT10 and still owning a 102ED, I have to say they're almost the perfect combo and not one I'd want to mess with.  The 120 f/8 isn't going to give you anything in between that the other two scopes don't do better.  I'd spend your money improving and accessorizing your XT10 as much as possible and enjoy what you have.

I have a few refractors , APO's and Achro's ( 60mm - 150mm ) and this is apples and oranges .

 

On your queery , I find my iStar 127mm f8 shows way more than my ED100 at f10 , yes the ED100 is CA free but even as the Istar achro shows minor CA , it shows way , WAY ! more detail on the moon and planets than both the ED100 and even my 110 f6 APO , that extra 27 and 17mm shows up at the eyepiece and on the good nights its the iStar that comes out she has superb  optics  .

 

The 127mm is not far behind my C9.25 on all objects , again this is seeing dependent  and your XT10 being close to my C9.25 in aperture would out perform the 120mm f8.3  but not by much if CA don't bug you and the 120 would be a much better G&G scope .

 

 

As you will find a good 120 class refractor can shine , like the 1000's of reviews out there  say so .

 

I have a friend down here with a SW 10 inch f 4.5 Dob with perhaps the best mirror system I have ever looked through , easily as good as my sadly sold Takahashi M210 , beautiful polish , figure and coatings  but even tho it takes 400x plus ,,, have you ever driven a Dob at 4- 600x ,,  it's not much fun , that's where a GEM ( EQ5 ) under a 120 class refractor shines ,, 2-300x on a good night with ease of driving .

 

Good luck .

 

Beanerds.


Edited by beanerds, 05 November 2019 - 06:45 AM.

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#47 clearwaterdave

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Posted 05 November 2019 - 07:19 AM

Thank you Beanerds.,I didn't get this to replace or to out do my other scopes.,It was a simple matter of it looked nice.,it was priced right.,and I like refractors.,lol.,And it does put out nice views..It cleaned up good.,and after making the scope and mount vixen friendly I think I will enjoy them both even more because I can mix an match to my hearts content.,cheers.,


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#48 Steve Cox

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Posted 05 November 2019 - 08:04 AM

I have a few refractors , APO's and Achro's ( 60mm - 150mm ) and this is apples and oranges .

 

On your queery , I find my iStar 127mm f8 shows way more than my ED100 at f10 , yes the ED100 is CA free but even as the Istar achro shows minor CA , it shows way , WAY ! more detail on the moon and planets than both the ED100 and even my 110 f6 APO , that extra 27 and 17mm shows up at the eyepiece and on the good nights its the iStar that comes out she has superb  optics  .

 

The 127mm is not far behind my C9.25 on all objects , again this is seeing dependent  and your XT10 being close to my C9.25 in aperture would out perform the 120mm f8.3  but not by much if CA don't bug you and the 120 would be a much better G&G scope .

 

 

As you will find a good 120 class refractor can shine , like the 1000's of reviews out there  say so .

 

I have a friend down here with a SW 10 inch f 4.5 Dob with perhaps the best mirror system I have ever looked through , easily as good as my sadly sold Takahashi M210 , beautiful polish , figure and coatings  but even tho it takes 400x plus ,,, have you ever driven a Dob at 4- 600x ,,  it's not much fun , that's where a GEM ( EQ5 ) under a 120 class refractor shines ,, 2-300x on a good night with ease of driving .

 

Good luck .

 

Beanerds.

I believe you might've misunderstood my post.  What you wrote is basically what I was getting at; the scopes clearwaterdave already has (had) already cover and fill the range that the 120 f/8 serves, so as a supplemental scope there's really no place for it in Dave's lineup.  But if it was an only scope then yes it would do very well.  But I understand Dave's sentiment that it's an awful tempting and beautiful scope and he can have lots of fun with it. 

 

OTOH, how often it gets out depends on how willing he is to haul it out and setup, being it's also a scope on the heavy side.  Having a 6" f/8 I fully understand that point as my 102ED/Voyager 2 sees much more time out, and if I changed the 6" f/8 out to a 10" dob, the dob would be out more often too.  But when my 6" f/8 was my only scope I was much more willing to lug it out.  In my new house though, it's much more difficult to get out the door and place as I need the ability to move around in the yard to see around neighbors trees, and a long focus refractor on heavy GEM can't do that.


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#49 clearwaterdave

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Posted 05 November 2019 - 09:28 AM

Hi Steve.,My set up is easy.,Only a few steps out the door.,and my scedule is open so time is not an issue.,I do have a hard time deciding who comes out to dance.,but it could be worse.,lol.,thanks for your replies.,


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#50 Sol Robbins

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Posted 05 November 2019 - 12:45 PM

Here's an old post on using a Cheshire/Sight Tube by Kerry R that should have definitely been pinned a long time ago:

 

https://www.cloudyni...limation-trick/

 

As others have said, collimate the focuser and lens tilt using Kerry's method. Then collimate the center of the star diagonal to the objectrive len's center and leave it there.


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